1. Field of the Invention
The present invention relates to a semiconductor device comprising an electrode pad for external connection (referred to as “electrode pad” hereinafter), a method and apparatus for testing the semiconductor device, and a method for manufacturing the semiconductor device. Particularly the invention relates to a semiconductor device comprising an electrode pad which contacts a test probe for electrical characteristic testing, a method and apparatus for testing the semiconductor device, and a method for manufacturing the semiconductor device.
2. Description of the Related Art
In a semiconductor device in the form of a chip, which is formed on a semiconductor substrate, electrical characteristic testing is performed by bringing a test probe of an electrical characteristic testing apparatus into contact with an electrode pad provided in the semiconductor device, which is so called “probing”, before mounting a semiconductor chip on the semiconductor device, to electrify the semiconductor device through the test probe. In such a semiconductor device, when bringing a test probe into contact with the surface of an electrode pad when performing probing, a contact damage called “probe damage” is generated on the surface of the electrode pad.
Recently, the area of an electrode pad is made small considerably in order to improve the integration degree of a semiconductor device. When performing so-called bonding where an electrode pad having the small area on which the probe damage is generated is connected an external electrode, the contact area between the external electrode and electrode pad decreases since asperities are formed on the surface of the electrode pad due to the probe damage. Therefore, the problem was that reliability of bonding is decreased. Particularly, a problem is generated when connecting an aluminum electrode pad with gold wire by ultrasonic bonding, because this bonding is performed by forming an alloy of aluminum and gold on the surface of the electrode pad, so the bonded surface is decreased due to the probe damage, whereby the bonding strength between the gold wire and electrode pad is decreased.
Japanese Unexamined Patent Application Publication No. 2002-329742 discloses a semiconductor device for solving such problems described above. In this semiconductor, a test pad for testing which abuts on a test probe, and a pad for bonding which is used for bonding are formed.
Further, Japanese Unexamined Patent Application Publication No. 7-147304 discloses a testing method for performing testing on a semiconductor device. With this testing method, probe damage is optically detected to test whether or not the probe damage protrudes from the allowable range. If the probe damage protrudes from the allowable range, an alarm is released, and then proceedings of the testing are stopped.
However, there are the following problems in the conventional testing. For example, in the semiconductor device comprising a pad for testing and a pad for bonding, the area occupied by the electrode pads on the semiconductor chip is large. In this case, the electrode pad is an obstacle to realizing high scale integration of the semiconductor. Particularly, with the recent multifunction of a semiconductor, the number of electrode pads is increasing, so it is difficult to achieve a multifunctional and highly integrated semiconductor device.
In the testing method where the probe damage is optically detected to judge whether or not the probe damage protrudes from the allowable range, sometimes the probe damage is detected by mistake. Also, testing is repeatedly performed using a probe card, the contact location of the probe end with respect to the electrode pad is gradually shifted. Specifically, location accuracy at the time when the probe is brought into contact with the electrode pad formed on the surface of the wafer is decreased due to deterioration of the physical strength of the probe. Furthermore, testing of a semiconductor is usually implemented before scribing a semiconductor wafer around the semiconductor chip. In this case, after testing is executed in the state where the probe is deteriorated, the probe damage is detected in a detection process. In a specific chip on the wafer, if the probe damage of the electrode pad which is detected in the detection process is defective in determination, the entire chips into which the probe contacts become defective in following tests which judge whether or not the probe damage protrudes from the allowable range. Therefore, there occur problems that yield cannot be improved, and that it is difficult to improve productivity.
Hence, It has now been discovered that testing cannot be performed accurately with the conventional testing method of a semiconductor device, whereby it is difficult to improve productivity.